RESOLVED FIXED 63493
Overlap map for compositing needs to consider clipping 
https://bugs.webkit.org/show_bug.cgi?id=63493
Summary Overlap map for compositing needs to consider clipping
Adrienne Walker
Reported 2011-06-27 16:38:20 PDT
The overlap map in RenderLayerCompositor currently doesn't consider clipping. So, if there is a large layer that is clipped, it may cause other layers to unnecessarily become composited, even though they aren't truly overlapping once clip is considered. See: http://crbug.com/85438
Attachments
Test case (1.37 KB, text/html)
2011-06-27 16:57 PDT, Adrienne Walker 		no flags
Details
Patch (14.17 KB, patch)
2011-06-27 17:49 PDT, Adrienne Walker 		simon.fraser: review+
DetailsFormatted DiffDiff
View All Add attachment proposed patch, testcase, etc.
Simon Fraser (smfr)
Comment 1 2011-06-27 16:52:45 PDT
I can haz testcase?
Adrienne Walker
Comment 2 2011-06-27 16:57:37 PDT
Created attachment 98815 [details] Test case Here's a test case. I have a patch too, but it changes the expected output from limit-layer-bounds-clipping-ancestor, so I need to clean that up first.
Adrienne Walker
Comment 3 2011-06-27 17:49:06 PDT
Created attachment 98830 [details] Patch
Adrienne Walker
Comment 4 2011-07-13 15:55:19 PDT
(In reply to comment #3) > Created an attachment (id=98830) [details] > Patch smfr: ping?
Simon Fraser (smfr)
Comment 5 2011-07-13 16:07:33 PDT
Comment on attachment 98830 [details] Patch View in context: https://bugs.webkit.org/attachment.cgi?id=98830&action=review > Source/WebCore/rendering/RenderLayerCompositor.cpp:569 > + IntRect clipRect = layer->backgroundClipRect(rootRenderLayer(), true); This is another walk up the layer tree, sadly.
James Robinson
Comment 6 2011-07-13 16:10:11 PDT
That one should hit cache (saved m_clipRects on the parent layer) most of the time, at least.
Simon Fraser (smfr)
Comment 7 2011-07-13 16:20:04 PDT
(In reply to comment #6) > That one should hit cache (saved m_clipRects on the parent layer) most of the time, at least. No, temporaryClipRects = true.
Adrienne Walker
Comment 8 2011-07-15 14:54:34 PDT
Committed r91114: <http://trac.webkit.org/changeset/91114>
Simon Fraser (smfr)
Comment 9 2012-05-19 07:56:22 PDT
The perf hit from this was significant: bug 84410
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